In one of its aspects, the present invention relates to a cleaning apparatus for use in a fluid treatment system. In another of its aspects, the present invention relates to a fluid treatment system comprising the cleaning apparatus.
Fluid treatment systems are known generally in the art.
For example, U.S. Pat. Nos. 4,482,809, 4,872,980 and 5,006,244 (all in the name of Maarschalkerweerd and all assigned to the assignee of the present invention and hereinafter referred to as the Maarschalkerweerd #1 Patents all describe gravity fed fluid treatment systems which employ ultraviolet (UV) radiation.
Such systems include an array of UV lamp frames which include several UV lamps each of which are mounted within sleeves which extend between and are supported by a pair of legs which are attached to a cross-piece. The so-supported sleeves (containing the UV lamps) are immersed into a fluid to be treated which is then irradiated as required. Depending upon the quality of the fluid which is being treated, the sleeves surrounding the UV lamps periodically become fouled with foreign materials, inhibiting their ability to transmit UV radiation to the fluid. For a given installation, the occurrence of such fouling may be determined from historical operating data or by measurements from the UV sensors. Once fouling has reached a certain point, the sleeves must be cleaned to remove the fouling materials and optimize system performance.
If the UV lamp modules are employed in an open, channel-like system (e.g., such as the one described and illustrated in Maarschalkerweerd #1 Patents), one or more of the modules may be removed while the system continues to operate, and the removed frames may be immersed in a bath of suitable cleaning solution (e.g., a mild acid) which may be air-agitated to remove fouling materials. Of course, this necessitates the provision of surplus or redundant sources of UV radiation (usually by including extra UV lamp modules) to ensure adequate irradiation of the fluid being treated while one or more of the frames has been removed for cleaning. This required surplus UV capacity adds to the capital expense of installing the treatment system. Further, a cleaning vessel for receiving the UV lamp modules must also be provided and maintained. Depending on the number of modules which must be serviced for cleaning at one time and the frequency at which they require cleaning, this can also significantly add to the expense of operating and maintaining the treatment system. Furthermore, this cleaning regimen necessitates relatively high labour costs to attend to the required removal/re-installation of modules and removal/re-filling of cleaning solution in the cleaning vessel. Still further, such handling of the modules results in an increased risk of damage to or breakage of the lamps in the module.
U.S. Pat. Nos. 5,418,370, 5,539,210 and 5,590,390 (all in the name of Maarschalkerweerd and all assigned to the assignee of the present invention and hereinafter referred to as the Maarschalkerweerd #2 Patents) all describe an improved cleaning system, particularly advantageous for use in gravity fed fluid treatment systems which employ UV radiation. Generally, the cleaning system comprises a cleaning sleeve engaging a portion of the exterior of a radiation source assembly including a radiation source (e.g., a UV lamp). The cleaning sleeve is movable between: (i) a retracted position wherein a first portion of radiation source assembly is exposed to a flow of fluid to be treated, and (ii) an extended position wherein the first portion of the radiation source assembly is completely or partially covered by the cleaning sleeve. The cleaning sleeve includes a chamber in contact with the first portion of the radiation source assembly. The chamber is supplied with a cleaning solution suitable for removing undesired materials from the first portion of the radiation source assembly.
The cleaning system described in the Maarschalkerweerd #2 Patents represents a significant advance in the art, especially when implemented in the radiation source module and fluid treatment system illustrated in these patents. However, there is still room for improvement.
For example, implementation of the cleaning system described in the Maarschalkerweerd #2 Patents can, in some cases, be problematic, particularly in pressurized fluid treatment systemsxe2x80x94e.g., in a fluid treatment system wherein flow of fluid has a pressure of at least 5 psi greater than the pressure of the cleaning fluid in the cleaning chamber. As will be described in more detailed hereinbelow, use of a conventional O-ring sealing arrangement as taught by the Maarschalkerweerd #2 Patents can result in catastrophic failure of the seals. While, in the past, this may not have been a significant problem in municipal wastewater treatment applications (i.e., after treatment, the fluid is then discharged into a stream, creek, river, lake or other body of water), more stringent environmental regulations are now encouraging the search for a solution to the problem. Also, clean water treatment systems present a unique set of challenges since the fluid being treated in the system is a source of potable/drinking water. If the cleaning system described in the Maarschalkerweerd #2 Patents were implemented in a pressurized clean water treatment system, there would be a likelihood of leakage of the cleaning solution from the chamber into the fluid being treated. Alternatively, there would be a likelihood of leakage of the fluid being treated into the cleaning system. It is desirable to avoid such leakage of cleaning solution to or from the cleaning system.
Thus, notwithstanding the advances in the art provided by the cleaning system taught in the Maarschalkerweerd #2 Patents, there remains a need in the art for a cleaning apparatus which may be implemented advantageously, inter alia, in a clean water treatment system.
It is an object of the invention to provide a cleaning system which obviates or mitigates at least one of the above-mentioned disadvantages of the prior art.
Accordingly, in one of its aspects, the present invention provides a cleaning apparatus for use in a fluid treatment system comprising a radiation source assembly, the cleaning apparatus comprising:
at least one cleaning sleeve in sliding engagement with the exterior of the radiation source assembly;
a cleaning chamber disposed in the at least one cleaning sleeve in contact with a portion of the exterior of the radiation source assembly and for being supplied with a cleaning solution, the cleaning chamber comprising an opening to an exterior of the cleaning sleeve;
a pressure equalization member disposed in the opening to provide a seal between the opening and the exterior of the cleaning sleeve, the pressure equalization member being moveable in response to a pressure gradient thereacross; and
drive means to translate the at least one cleaning sleeve along the exterior of the radiation source assembly.
In another of its aspects, the present invention provides, a fluid treatment device comprising a housing for receiving a flow of fluid, the housing comprising:
a fluid inlet;
a fluid outlet;
a fluid treatment zone disposed between the fluid inlet and the fluid outlet;
a radiation source assembly disposed in the fluid treatment zone for treatment of the flow of fluid; and
a cleaning apparatus comprising: at least one cleaning sleeve in sliding engagement with the exterior of the radiation source assembly; a cleaning chamber disposed in the at least one cleaning sleeve in contact with a portion of the exterior of the radiation source assembly and for being supplied with a cleaning solution, the cleaning chamber comprising an opening to an exterior of the cleaning sleeve; a pressure equalization member disposed in the opening to provide a seal between the opening and the exterior of the cleaning sleeve, the pressure equalization member being moveable in response to a pressure gradient thereacross; and drive means to translate the at least one cleaning sleeve along the exterior of the radiation source assembly.